Question

Tìm x để biểu thức B = \(x-\sqrt{x}+1\) có GTNN.

Answer 1

ĐKXĐ: \(x\ge0\)

\(B=\left(x-\sqrt{x}+\dfrac{1}{4}\right)+\dfrac{3}{4}=\left(\sqrt{x}-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\)

\(B_{min}=\dfrac{3}{4}\) khi \(x=\dfrac{1}{4}\)